Service to universal joints that are factory lubricated is limited to replacement when signs of excessive wear are present. The universal joints provided with lubrication fittings are only lubricated with a hand operated low-pressure grease guns. Use of a high-pressure grease gun will damage the seals, resulting in early failure of the universal joint.

Another area to be concerned with when servicing the universal joints is the slip yoke (joint). Slip yokes may be lubricated from the transmission or lubricated through a lubrication fitting.

NOTE

Always consult the manufacturer's service manual for lubrication intervals and proper lubricants to be used.

A worn universal joint is the most common drive line problem, causing squeaking, grinding, clunking, or clicking sounds. The grease inside the joint can dry out. The roller bearings will wear small indentations in the cross. When the bearings try to roll over these dents, a loud metal-on-metal grinding or chirp sound can result.

Quite often, a worn U-joint is discovered when the transmission is placed in REVERSE. When the vehicle is backed up, the roller bearing is forced over the wear indentation against normal rotation. When this occurs, the rollers will catch on the sharp edges in the worn joint, causing even a louder sound.

UNIVERSAL JOINT DISASSEMBLY.- The universal joint may require removal and disassembly to enable you to check the condition of the joint physically. Steps for the removal and disassembly of a U-joint are as follows:

1. Raise the vehicle and place it on jack stands.
2. Scribe the alignment marks on the differential yoke and universal joint, so drive shaft balance is ensured upon reassembly.
3. Unbolt the rear joint from the differential. If used, also unbolt the center support bearing. Pry the shaft forward and lower the shaft slightly.

CAUTION

Do NOT allow the full weight of the drive shaft to hang from the slip yoke. Support the drive shaft to prevent damage to the extension housing, rear bushing, and front U-joint.

4. Wrap the tape around the caps to prevent them from falling off and spilling the roller bearings.
5. Slide the drive shaft out of the transmission. If the transmission lubricant begins to leak, install a plastic plug into the extension housing.
6. Before disassembling the universal joint, especially constant velocity joints, scribe mark each component. The marks will show you how to reassemble the joint.
7. Clamp the drive shaft yoke in a vise. Do NOT clamp the weaker center section of the drive shaft or it will bend. If used, remove the snap rings, using a screwdriver, snap-ring pliers, or needle nose pliers.

CAUTION

Wear safety glasses to protect your eyes in case the snap rings fly out of the universal joint during removal.

8. Use two sockets- one LARGER than the bearing cap and one SMALLER than the bearing cap. Place the SMALLER socket on the bearing cap of the universal joint (fig. 5-11). The LARGER socket is to be placed over the outside diameter of the bearing cap on the opposite side of the joint (fig. 5-11).
9. With both sockets and the universal inside the vise, slowly tighten the vise to force the bearing caps out of the yoke. Use the same procedure on the remaining bearing caps, as required.

Figure 5-11.- Universal joint removal.

Normally, a universal joint is replaced anytime it is disassembled. However, if the joint is relatively new, you can inspect, lubricate, and reassemble it.

During the inspection, clean the roller bearings and other parts in solvent. Then check the cross and rollers for signs of wear. If the slightest sign of roughness or wear is found on any part, REPLACE the U-joint.